Issue Description: Marker created using command in-game saved to plugins\dynmap\markers.yml, but Marker created using api (with persistent param set to true )does not save and will be lost if the server restart
API code:

markerset.createMarker(null, "Chest", "world", chest.getX(), chest.getY(), chest.getZ(), dapi.getMarkerAPI().getMarkerIcon("chest"), true );

• Dynmap Version: v3.1-beta5
• Server Version: spigot 1.16.4
• Pastebin of Configuration.txt: default
• Server Host (if applicable): local

[x] I have looked at all other issues and this is not a duplicate
[x] I have been able to replicate this

Confirm that the marker set was created as persistent: if the marker set isn't persistent, the markers in that set cannot be.

[dynmap] Marker API has been requested, but is not enabled.  Uncomment or add 'markers' component to configuration.txt.

What does this error mean? @mikeprimm